This invention relates to multilayer integrated electronic circuits.
More particularly, the present invention relates to electrical integrated circuits which utilize integrated capacitors and inductors.
Integrated circuits utilize a variety of circuit elements to process electrical signals. The circuit elements fall into two categories. One category includes active elements, such as transistors. The second category includes passive elements, such as resistors, capacitors, and inductors. Passive elements play an important role in signal processing circuitry, such as in electronic filters.
However, the integration of passive elements into an integrated circuit creates numerous problems. One problem that arises is that electrical coupling between adjacent circuit elements within the same section can increase the crosstalk and noise within the electrical circuit. Crosstalk and noise may produce unwanted transmissions and results in performance degradation in communication systems utilizing these components. For example, FIG. 1 illustrates an isometric view of an integrated circuit 5 used in the prior art which utilizes an integrated inductive element 10 with a resistance and an integrated capacitive element 12 positioned adjacent to or within a dielectric substrate 7, wherein integrated capacitive element 12 defines a surface. Integrated inductive element 10 has a width 15 that is parallel with the surface of integrated capacitive element 12. Further, integrated inductive element 10 induces a circumferential magnetic field 17 that is perpendicular to both the surface of integrated capacitive element 12 and width 15. Circumferential magnetic field 17 will therefore induce eddy currents which will impede the current flow and increase the resistance of integrated inductive element 10. Circumferential magnetic field 17 will also make the current density across width 15 non-uniform, i.e. in this example, the current density along the inner edge of integrated inductive element 10 is approximately twice the current density along the outer edge. Consequently, the increased resistance of integrated inductive element 10 will degrade the quality factor and performance of the circuit.
Crosstalk also occurs between circuit elements of different circuit sections. One method to decrease the electrical coupling between adjacent circuit sections is to insert an isolation wall. For example, FIG. 2 illustrates a prior art elliptical filter 20 which utilizes two adjacent elliptical filter sections 22 and 24 separated by an isolation wall 26. The primary coupling occurs between the inductive components in adjacent circuit sections. The purpose of isolation wall 26 is to prevent the induced circumferential magnetic field from elliptical filter section 22 from penetrating into elliptical filter section 24, and vice versa. However, the problem with using isolation wall 26 is that the size of the circuit is increased because the elliptical sections must be spaced further apart to accommodate the isolation wall. Thus, an isolation wall has a size that is prohibitive and dramatically increases the cost of the electronic circuit.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
A method of utilizing passive circuit components in an integrated circuit involves orienting the integrated inductive elements at an angle with the integrated capacitive elements and with the width of the integrated inductive elements so as to minimize the magnitude of the eddy currents induced by the circumferential magnetic field created by the integrated inductive elements. The method also involves orienting adjacent integrated inductive elements so that the circumferential magnetic fields are anti-parallel in between integrated inductive elements and, consequently, cancel to minimize electromagnetic coupling. Minimizing electromagnetic coupling significantly reduces the crosstalk between adjacent inductive elements and improves the quality factor and frequency response of the integrated circuit.